Benchmark ZWB 7-29 CC1 Installation And Servicing page 75

d3
flashing.
Wrong signal from pin 8-9 (open?).
Check
B Turn ON the appliance.
1.
B Measure voltage between Termi-
nal 4 and Terminal 8.
Voltage ≅ 24 V DC?
2. Existing heat store thermostat con-
nected to Terminals 7, 8 and 9?
3. Break in connecting lead?
4. The PCB control board is damaged.
7 181 465 346 GB (03.02)
Action
↓2.
yes:
↓3.
no:
B Power OFF the appliance.
yes:
B Fix the additional bridge 8-9 in the right position
and close the screws.
B Turn ON the appliance.
d3? ↓3.
↓4.
no:
B Power OFF the appliance.
yes:
B Plug the connection wire.
B Turn ON the appliance.
d3? ↓4.
↓4.
no:
B Make a note of the altered service settings (see
table 1, "First Service Level; Values that can be
modified" at page 8 and table 5, "Secondary
Service Level; Values that can be modified" at
page 11).
B Power OFF the appliance.
B Disconnect the boiler electrical connection.
B Change PCB control board.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
B Restore service settings previously noted down.
Failure identification procedure
27